UnityEngine.Texture2D.GetPixel C# (CSharp) Method

        public Color GetPixel(int x, int y)
        {
            Color color;
            INTERNAL_CALL_GetPixel(this, x, y, out color);
            return color;
        }

    public static Texture2D CalculateNormalMap(Texture2D source, float strength)
    {
        Texture2D result;
        float xLeft, xRight;
        float yUp, yDown;
        float yDelta, xDelta;
        var pixels = new Color[source.width * source.height];
        strength = Mathf.Clamp(strength, 0.0F, 10.0F);        
        result = new Texture2D(source.width, source.height, TextureFormat.ARGB32, true);
        
        for (int by = 0; by < result.height; by++)
        {
            for (int bx = 0; bx < result.width; bx++)
            {
                xLeft = source.GetPixel(bx - 1, by).grayscale * strength;
                xRight = source.GetPixel(bx + 1, by).grayscale * strength;
                yUp = source.GetPixel(bx, by - 1).grayscale * strength;
                yDown = source.GetPixel(bx, by + 1).grayscale * strength;
                xDelta = ((xLeft - xRight) + 1) * 0.5f;
                yDelta = ((yUp - yDown) + 1) * 0.5f;

                pixels[bx + by * source.width] = new Color(xDelta, yDelta, 1.0f, yDelta);
            }
        }

        result.SetPixels(pixels);
        result.wrapMode = TextureWrapMode.Clamp;
        result.Apply();
        return result;
    }